During use, microprocessors may be exposed to external conditions which may cause internal data bits within or being processed by the microprocessor to change. Commonly, these events are classified as single event upsets (SEU). Conditions giving rise to SEU may include ambient radiation (including protons, x-rays, neutrons, cosmic rays, electrons, alpha particles, etc.), electrical noise (including voltage spikes, electromagnetic interference, wireless high frequency signals, etc.), and/or improper sequencing of electronic signals or other similar events. The effects of SEU conditions can include the processing of incorrect data or the microprocessor may temporarily or permanent hang, which may be reference to as single event functional interrupt (SEFI), for a temporary or permanent condition.
A number of solutions to avoid or correct for these events have been developed, and include modifying the manufacturing process for the microprocessor. For example, microprocessor may utilize temporal redundancy or spatial redundancy in an effort to mitigate the likelihood of SEUs. While these systems have proven somewhat effective in reducing or avoiding SEU and SEFI events, several shortcomings have been identified. For example, using spatial redundancy in a triple modular redundant design allows three microprocessors to operate in parallel to detect and correct for single event upsets and functional interrupts, but require two additional microprocessors and support circuits (e.g. memory) causing additional power and synchronization problems. Another solution is to manufacture the microprocessor integrated circuits (IC) on radiation tolerant processes, which historically lag commercial devices by two to three generations. More specifically, today's radiation-tolerant IC production processes produce devices utilizing 0.35 micrometer geometries while non-radiation tolerant devices typically utilize 0.13 micro-meter geometry. The effect of the larger geometry is much slower performance and higher power consumption for the microprocessor.
In light of the foregoing, there is an ongoing need for high performance, low power consumption radiation tolerant systems and devices, that mitigate the problem of single event functional interrupt (SEFI), also known as environmental induced hangs.